LITTLE ROCK — Arkansas legislative leaders on Monday vowed to work across party lines after an election where Republicans won control of the House and Senate for the first time in 138 years, opening a session that will be dominated by questions about the state’s Medicaid program.

Members of the House and Senate gathered at the Capitol for the start of this year’s legislative session, with the Republican leaders of both chambers promising to set aside party labels in the debate surrounding a $138 million shortfall in the state’s Medicaid budget and a proposal to expand the program under the federal health care law.

“To me, this session is not all about Medicaid, but how we treat each other,” Senate President Michael Lamoureux, R-Russellville, told the 35-member Senate after being sworn in for the start of the 89th General Assembly. House Speaker Davy Carter, R-Cabot, also urged bipartisanship in a speech that didn’t mention Medicaid or other issues the Legislature faces this year.

“This won’t be a cakewalk,” he said. “We have serious issues ahead that will require vigorous debate.”

Arkansas Department of Human Services officials have blamed the Medicaid shortfall partly on the program’s growing costs and a reduction in the federal matching rate tied to the state’s per-capita income.

The shortfall comes even after Democratic Gov. Mike Beebe proposed $90 million in additional general revenue and $140 million from the state surplus to help the program.

To cover the deficit, DHS officials have proposed a series of cuts that include removing thousands of seniors from nursing home care, eliminating an insurance program for low-income workers, cutting reimbursements to providers and eliminating non-emergency dental care for adults.

Carter and Lamoureux have said they believe the cuts can be avoided by using the rest of the state’s expected $300 million surplus and growth in revenues in next year’s budget.

At the same time, lawmakers are considering a proposal to expand Medicaid’s eligibility under the federal health care law. The law calls for the federal government to pay the full tab for the Medicaid expansion when it begins in 2014. After three years, states must pay a gradually increasing share that tops out at 10 percent of the cost.

The U.S. Supreme Court in June upheld the health care law, but justices said the federal government could not take away states’ existing federal Medicaid dollars if they refused to expand.

Beebe supports the move, saying it would save the state money by cutting down the costs Arkansas hospitals face for uncompensated care

The move, however, faces long odds. Expansion would require a three-fourths vote in both chambers, and many Republicans won in November after vowing to oppose the federal law at the state level.

Republicans control 21 of the 35 seats in the Senate and 51 of the 100 seats in the House.

Lamoureux and other legislative leaders have left open the possibility of a compromise that would allow some form of expansion in exchange for changes to the Medicaid program that they believe would save money, such as requiring drug testing of some people.

“I don’t know of anyone who is jumping up and down for expansion in our caucus,” said Senate Majority Leader Eddie Joe Williams, R-Cabot.

Sen. Paul Bookout, D-Jonesboro, who supports the expansion, said he hoped lawmakers who campaigned against it could set aside last year’s election and look at the proposal’s merits.

“We’re not talking about those looking for a handout. We’re talking about those individuals that work hard also, but can’t afford health insurance,” Bookout said. “We’re talking about rural hospitals and access to health care in a lot of the areas of this state that if we don’t support this, are no longer going to be able to keep their doors open.”

Carter said the House would begin “substantive discussions” on Medicaid in the next two or three weeks, but he declined to be more specific Monday about the timeline.

Beebe planned to deliver his State of the State to the House and Senate on Tuesday morning, marking his last regular legislative session. Beebe is term-limited and cannot run for re-election next year. The Democratic governor said much of his speech will focus on the issues surrounding Medicaid and his proposed $4.9 billion budget.

“There’s not going to be any huge surprises,” Beebe said. “We’re going to talk about the same stuff we’ve been talking about.”